Wireless camera tracking system

ABSTRACT

Various arrangements of wireless tracking systems are presented. A tag device may be presented that include a first plurality of antennas. Each antenna of the first plurality of antennas may have an antenna radiation pattern pointed in a different direction. The tag device may include a wireless transmitter interface that transmits via each antenna of the first plurality of antennas. The wireless tracking system may also include a tracker device that tracks a direction to the tag device. The tracker device may include a second plurality of antennas. Each antenna of the second plurality of antennas may have an antenna radiation pattern pointed in a different direction. The tracker device may include a wireless interface receiver that performs a plurality of signal strength measurements using the second plurality of antennas.

BACKGROUND

In certain scenarios, a cameraman may not be practical or available inorder to point a camera. Rather, a motorized targeting system may bedesired that points a camera at a particular subject. Such anarrangement may allow for video or still capture of a subject, despitethe subject moving. However, keeping the camera targeted on the subjectcan be a difficult task, especially when various obstacles are presentin the vicinity of the motorized targeting system and/or the subject. Ofparticular difficulty may be the situation where obstacles are locatedbetween the motorized targeting system and the subject.

SUMMARY

Various embodiments are described related to a wireless tracking system.In some embodiments, a wireless tracking system is described. The systemmay include a tag device. The tag device may include a first pluralityof antennas, each antenna of the first plurality of antennas having anantenna radiation pattern pointed in a different direction. The tagdevice may include a wireless transmitter interface that transmits viaeach antenna of the first plurality of antennas. The tag device mayinclude a processing system that causes the wireless transmitterinterface to transmit a sequence of messages via the first plurality ofantennas. Each message of the sequence of messages may be transmittedvia a different antenna of the first plurality of antennas. Each messageof the sequence of messages may be transmitted for a defined timeperiod. Each message of the sequence may include an identifier of theantenna of the first plurality of antennas from which it is transmitted.The system may include a tracker device that tracks a direction from thetracker device to the tag device. The tracker device may include asecond plurality of antennas, each antenna of the second plurality ofantennas having an antenna radiation pattern pointed in a differentdirection. The tracker device may include a wireless interface receiverthat performs a plurality of signal strength measurements. Each signalstrength measurement may be made via a different antenna of the secondplurality of antennas during the defined time period. The system mayinclude a processing system configured to receive the plurality ofsignal strength measurements. The processing system may be configured todetermine the direction from the tracker device to the tag device usingthe plurality of signal strength measurements.

Embodiments of such a system may include one or more of the followingfeatures: The wireless tracking system may include a motorized trackingassembly. The processing system of the tracker device may be furtherconfigured to output the direction to a motorized tracking assembly. Themotorized tracking assembly may be configured to physically point amount of the motorized tracking assembly based on the direction data.The motorized tracking assembly may be configured to have a video cameramounted onto the mount. The second plurality of antennas may have agreater number of antennas than the first plurality of antennas. Thefirst plurality of antennas may include four antennas with each antennaof the first plurality of antennas having a 90 degree radiation pattern.The second plurality of antennas may include twenty-four antennas witheach antenna of the second plurality of antennas having a 15 degreeradiation pattern. The processing system may be configured to determinethe direction from the tracker device to the tag device using theplurality of signal strength measurements. The processing system maydetermine that the signal strength measurements made by the wirelessinterface receiver from the sequence of messages transmitted by thefirst plurality of antennas are inconclusive as to which of the firstplurality of antennas is pointed towards the tracker device. Theprocessing system may, in response to the determining, identify a firstantenna of the second plurality of antennas and a second antenna of thesecond plurality of antennas through which signal strength measurementswere made that were below a minimum threshold value and between whichthe signal strength measurements were above the minimum threshold value.The processing system may determine the direction from the trackerdevice to the tag device as a center of an angle between the firstantenna and the second antenna. The wireless transmitter interface maytransmit using the IEEE 802.11a standard. Each message may furtherinclude a tag identifier that identifies the tag device. The tag devicemay further include a battery compartment and the tag device may beexclusively powered by one or more batteries installed in the batterycompartment.

In some embodiments, a method of using a wireless tracking system isdescribed. The method may include transmitting, by a tag device of thewireless tracking system, a signal via each tag antenna of a pluralityof tag antennas of the tag device. Each tag antenna of the plurality oftag antennas may be pointed in a different direction. Each signal may betransmitted sequentially. The method may include receiving, by a trackerdevice of the wireless tracking system, each signal transmitted via eachtag antenna using each tracker antenna of a plurality of trackerantennas of the tracker device. Each signal may identify the tag antennaof the plurality of tag antennas of the tag device from which the signalwas transmitted. The method may include performing, by the trackerdevice, a plurality of signal strength measurements for each signalreceived via each tracker antenna of the plurality of tracker antennas.The method may include determining the direction from the plurality oftracker antennas to the tag device using the plurality of signalstrength measurements.

Embodiments of such a method may include one or more of the followingfeatures: The method may include outputting, by the tracker device,direction data indicative of the direction to a motorized trackingassembly, and the motorized tracking assembly may be configured tophysically point a mount of the motorized tracking assembly based on thedirection data. The method may include capturing video using a videocamera that is mounted to the mount of the motorized tracking assembly.The plurality of tracker antennas may have a greater number of antennasthan the plurality of tag antennas. Determining the direction to the tagdevice using the plurality of signal strength measurements may includedetermining that the signal strength measurements made from the signalstransmitted by the first plurality of antennas are inconclusive as towhich of the plurality of tag antennas may be pointed towards theplurality of tracker antennas. The method may include, in response tothe determining, identifying a first antenna of the plurality of trackerantennas and a second antenna of the plurality of tracker antennasthrough which signal strength measurements were made that were below aminimum threshold value and between which the signal strengthmeasurements were above the minimum threshold value. The method mayinclude determining the direction to the tag device as a center of anangle between the first antenna and the second antenna. The tag devicemay transmit the signals using the IEEE 802.11a standard. Each signalmay further include a tag identifier that identifies the tag device. Themethod may include exclusively powering the tag device using one or moreon-board batteries. The plurality of tag antennas may include four tagantennas. The plurality of tracker antennas may include twenty-fourtracker antennas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a wireless camera tracking system.

FIGS. 2A-2D illustrate embodiments of tag antenna transmission patternsand tracker antenna receiver patterns.

FIG. 3 illustrates an example of a scenario in which an obstacle ispresent that affects signal strength measurements made by the tracker.

FIG. 4 illustrates a second example of a scenario in which multipleobstacles are present that affects signal strength measurements made bythe tracker.

FIG. 5 illustrates a third example of a scenario in which multipleobstacles are present that affects signal strength measurements made bythe tracker.

FIG. 6 illustrates an embodiment of using null signal strengthmeasurements to estimate a direction of a tag.

FIG. 7 illustrates an embodiment of a method for using a wireless cameratracking system.

DETAILED DESCRIPTION

A camera tracking system may include a tag device (referred to as a“tag” for short) and a tracker device (referred to as a “tracker” forshort). The tag may be affixed to or otherwise placed in the vicinity ofa subject that may move. For example, the subject may be a person,animal, robot, machinery, or other object that is desired to be tracked.The tag may transmit messages via multiple antennas. Each of theseantennas may be pointed in a different direction. For instance, fourantennas may be arranged that each have a main lobe of an antenna beampattern offset by 90° in a plane parallel to the ground. Each antennamay be used to transmit a message that identifies: 1) the tag; and 2)the antenna of the tag through which the message was transmitted. Eachantenna of the tag may be used to transmit in a sequential or repeatingpattern. The amount of time during which each antenna transmits may beconstant, such that the transmissions can be understood as a timedivision multiple access (TDMA) arrangement.

A tracker may receive the transmitted messages via multiple antennas.The tag may transmit using a first antenna during a first the timeperiod. During this time period, the tracker may make a received signalstrength indication (RSSI) measurement on each of the tracker'santennas. The tracker may repeat these measurements for each time periodduring which a different antenna of the tag is transmitting a message.Therefore, after a number of time periods equal to the number ofantennas of the tag, the tracker may have made signal strengthmeasurements using each of the tracker's antennas on signals transmittedby each of the tag's antennas.

Using the signal strength measurements made by the tracker, the trackercan cause a motorized tracking assembly to point in a direction of thetag. In certain situations, such as when the signal strength received bythe tracker from a particular antenna of the tag, has a greater signalstrength (and, possibly, a flat wave front), it may be determined thatthe particular antenna of the tag is pointed in the direction of thetracker (and the signal received from that antenna is unlikely to bereflecting off of an obstacle). In such a scenario, the motorizedtracking assembly may be caused to point in the direction in which thetracker's antenna that received the highest signal strength from thehighest signal strength antenna of the tag is pointed. In othersituations, such as where one or more obstacles are present between orin the vicinity of the tracker and tag, a more detailed analysis, suchas detailed in relation to method 700 of FIG. 7, may be performed todetermine in which direction the tag is located.

While embodiments detailed herein are focused on using a motorizedtracking assembly to point a camera attached to a mount of the motorizedtracking assembly, it should be understood that such a tracking systemmay be used to point other forms of systems or devices. For example,such an arrangement may be used for pointing a telescope or binocularsaimed at a moving target on the earth or in the air. Such an arrangementmay be used for pointing a laser, a spotlight, an audio speaker, aplatform, or some other device or system that can be coupled with amotorized tracking assembly. In still other embodiments, the trackingsystem may not physically point a system or device in the direction ofthe tag, but rather may output the determined direction to anothersystem or device for use externally. For instance, such a system may beused for generally tracking the whereabouts of an employee in awarehouse or office building.

Greater detail is provided in relation to the figures. FIG. 1illustrates an embodiment of a wireless camera tracking system 100.Wireless camera tracking system 100 may include: tag device 110(referred to as “tag 110” for short), tracker device 120 (referred to as“tracker 120” for short), motorized tracking assembly 130, and camera140. Tag device 110 may be a device that is attached to, affixed to, orotherwise placed or in the vicinity of an object, animal, or person thatis desired to be tracked by tracker 120. For example, tag 110 may beattached to: a speaker at a presentation, a pet, a performer, a ball orpuck, or an athlete. Tag 110 may include: processing system 111,configuration settings and device parameters 112, wireless transmitterinterface 113, antenna array 114, antennas 115, battery assembly 116,and fastener 117. Fastener 117 may be used to attach tag 110 to theobject, animal, or person to be tracked. Fastener 117 may be varioustypes of fasteners, such as: glue, tape, a hook-and-loop system, a nail,a screw, a wearable bracelet, anklet, pendant, etc. since tag 110 isrelatively small, fastener 117 may be selected based on the object,animal, or person to which tag 110 is to be fastened. In someembodiments, fastener 117 is not needed. For example, tag 110 may beplaced in a person's pocket. In still other embodiments, tag 110 may bepermanently installed as part of another device. For instance, tag 110may be incorporated in a microphone.

Processing system 111 may include one or more processors and/or othercomputerized components and may perform onboard processing on tag device110. Processing system 111 may access configuration settings and deviceparameters 112 to determine how and what data should be transmitted viawireless transmitter interface 113. Configuration settings and deviceparameters 112 may indicate an identifier for tag 110. This identifiermay be intended to be unique from other tag devices and/or otherwireless devices in the area. In some embodiments, the tag identifier isa MAC address. Configuration settings a device parameters 112 may alsoinclude identifiers for individual antennas of antenna array 114.Configuration settings and device parameters 112 may also includesettings that indicate how frequently tag 110 should transmit via eachantenna of antenna array 114 and, possibly, how long each datatransmission should last. Such a configuration settings and deviceparameters 112 may be updated by processing system 111 in response tocommand messages received from tracker device 120 or some other device.For instance, in a situation where a large amount of obstacles arepresent, tag device 110 may receive a command from tracker device 120 orsome other source that indicates tag device 110 should transmit morefrequently and/or with a higher power.

Wireless transmitter interface 113 may transmit messages via antennas115 of antenna array 114. Wireless transmitter interface 113 may receivedata from processing system 111 to transmit. In some embodiments,wireless transmitter interface 113 appends data to data received fromprocessing system 111 to be broadcast via antennas 115. For instance,processing system 111 may not be able to determine which antenna amessage will be transmitted from. Rather, wireless transmitter interface113 may make such a determination and append an identifier of theparticular antenna. Wireless transmitter interface 113 may communicateusing one or more wireless communication protocols. In some embodiments,wireless transmitter interface 113 communicates using the IEEE 802.11astandard. The standard may be selected because it is a relatively highpower communication standard and there may be relatively littleinterference from other devices in the vicinity of tag device 110. Itshould be understood that in other embodiments, different communicationstandards may be used. For example, Bluetooth or Wi-Fi may be usedinstead. Wireless transmitter interface 113 is referred to as atransmitter, however it should be understood that this is to indicatetag 110 primarily transmits messages to tracker device 120. It should beunderstood that wireless transmitter interface 113 can function as atransceiver and receive messages from tracker 120 and/or other devicesvia antenna array 114.

Wireless transmitter interface 113 may communicate using antenna array114. Antenna array 114 includes multiple antennas that are each arrangedsuch that the primary lobe of each antennas radiation pattern points ina different direction. For example, each of four antennas 115 (115-1,115-2, 115-3, and 115-4) may have their primary antenna lobes offsetfrom each other by 90° in a plane parallel to the ground. While fourantennas 115 are illustrated, it should be understood that this numberof antennas is exemplary; greater or fewer numbers of antennas 115 maybe present in other embodiments. For example, it may be possible to moreaccurately identify the location of tag 110 if eight antennas arepresent that have their primary antenna lobes offset from each other by45°. In some embodiments, each of antennas 115 may be the same antennadesign, but mounted in a different physical arrangement within or on tag110.

Wireless transmitter interface 113 may which antenna of antenna array114 is used to transmit a message. For example, wireless transmitterinterface 113 may transmit using antenna 115-1, then transmit a messageusing antenna 115-2, then transmit a message using antenna 115-3, thentransmit a message using antenna 115-4, and then repeat the sequence. Insome embodiments, processing system 111 may instruct wirelesstransmitter interface 113 which antenna of antenna array 114 to use totransmit a particular message.

Battery assembly 116 may be used to house one or more batteries. The oneor more batteries housed by battery assembly 116 may be used toexclusively power tag device 110. That is, components of tag 110 may notreceive power from a source other than battery assembly 116.Accordingly, tag 110 may be understood to be a wireless device since itwirelessly communicates and has an onboard power source.

Tracker device 120 may be used to determine a direction to tag device110. Tracker device 120 may include: processing system 121, wirelessreceiver interface 122, antenna array 123, antennas 124, signal strengthdatastore 125, and direction output interface 126. Processing system 121may include one or more processors that are in communication withwireless receiver interface 122, direction output interface 126, andsignal strength datastore 125. Processing system 121 may be used toanalyze the received signal strength measurements and determine adirection in which tag 110 is located based on such signal strengthmeasurements.

Wireless receiver interface 122 may receive messages transmitted by tag110 via antenna array 123. When a message is transmitted using aparticular antenna of antenna array 114 of tag 110, tracker 120 may useeach antenna of antenna array 123 to receive a portion of the message.For example, various segments of the message may be a repeating patternthat is transmitted and that is assessed for signal strength. Wirelessreceiver interface 122 may perform various signal strength measurements,which can be referred to as RSSI measurements. These measurements may beoutput to processing system 121 and may be stored in signal strengthdatastore 125. Each signal strength measurement may be linked with anindication of an antenna of antenna array 114 from which the messagethat the single strength measurement was performed on was transmitted.Each signal strength measurement may also be linked with an indicationof an antenna of antenna array 123 through which wireless receiverinterface 122 measured the received signal strength.

Wireless receiver interface 122 may make the single strengthmeasurements using antennas 124 of antenna array 123. Each of antennas124 may be of a similar design, but may be physically arranged such thata main lobe of each antenna is pointed in a different direction. Forexample, in some embodiments each of antennas 124 have a main lobe thatis pointed 45° offset from each other in a plane parallel to the ground.In some embodiments, many more antennas are present as part of antennaarray 123. For example, in some embodiments 24 antennas are part ofantenna array 123 with each antenna being 15° offset from each other ina plane parallel to the ground. Such antennas may have a main antennalobe of approximately 15° in width. Therefore, it should be understoodthat antenna array 123 may have a greater or fewer number of antennasthan as illustrated in wireless camera tracking system 100. It should beunderstood that in many embodiments, antenna array 123 has a greaternumber of antennas than antenna array 114. The greater number ofantennas present as part of antenna array 123 may increase the accuracyof it direction determined by processing system 121 to tag device 110.For example, if 24 antennas are present with a 15° offset, this 15°offset may also be the margin of error for determination of direction totag 110.

Wireless receiver interface 122 may be configured to receive signalstrength measurements, but may also receive messages. Therefore, when amessages transmitted by tag 110, a portion of the message may includedummy data that is exclusively intended for having signal strengthmeasurements performed on it. However, other data may be transmittedthat is to be read by wireless receiver interface 122, such as anindication of an identifier of tag 110 and/or an identifier of theantenna of antenna array 114 which transmitted the message. Further,other data may be reported back by tag 110, such as a battery level,signal strength on data received by tag 110 from tracker 120, or otherinformation that may be available locally to tag 110. While wirelessreceiver interface 122 is referred to as receiver, it should beunderstood that the use of the word receiver is to emphasize thattracker 120 receives signal strength measurements from tag 110. Wirelessreceiver interface 122, or some separate transceiver present on tracker120, may be used to transmit data, such as to tag 110. Wireless receiverinterface 122 may be configured to use whichever wireless communicationprotocol is in use by wireless transmitter interface 113.

Signal strength datastore 125 may be a non-transitory computer readablemedium, such as a random-access memory. Signal strength datastore 125may be used to store signal strength measurements made using antennaarray 123 by wireless receiver interface 122. The number of signalstrength measurements stored to signal strength datastore 125 may be thenumber of antennas in antenna array 123 multiplied by the number ofantennas present in antenna array 114. That is, for each antenna inantenna array 114, a signal strength measurement may be made using eachantenna of antenna array 123. Once a complete set of single strengthmeasurements has been made and stored to signal strength datastore 125,processing system 121 may analyze such signal strength measurements.

Processing system may determine the direction in which tag 110 islocated by performing processing as detailed in method 700. In someembodiments, the direction determined is two-dimensional. For example,the direction may be determined in a plane parallel to the ground. Inother embodiments, a three-dimensional direction may be determined. Oncea direction has been determined, in indication of the direction, such asan angle off of a defined axis, may be output by processing system 121to direction output interface 126. Direction output interface 126 mayoutput the determined direction to an external device or system. Inother embodiments, an external system or device may query directionoutput interface 126 when the external device or system wants to knowthe direction of tag device 110.

In some embodiments, the direction is output to motorized trackingassembly 130. Motorized tracking assembly 130 may have a mount,processing system, and one or more motors that allows the motorizedtracking assembly 130 to rotate the mount in various directions within aplane or rotate the mount to point in three dimensions. The motorizedtracking assembly 130 may rotate the mount based on the receiveddirection data from direction output interface 126. In some embodiments,camera 140, which may be a still or video camera, may be mounted ontothe mount of motorized tracking assembly 130. When such a camera ismounted on motorized tracking assembly 130, camera 140 may stayapproximately aimed at the object, person, or animal to which tag device110 is a fixed. To account for an amount of error in determining thedirection to tag device 110 due to the number of antennas 124 in antennaarray 123, the field of view of camera 140 may be maintainedsufficiently wide to accommodate this resolution error range.

Tracker device 120 may have battery assembly 127. Battery assembly 127may be used to house one or more batteries. The one or more batterieshoused by battery assembly 127 may be used to exclusively power tracker120. That is, components of tracker 120 may not receive power from asource other than battery assembly 127. Accordingly, tracker 120 may beunderstood to be a wireless device since it wirelessly communicates andhas an onboard power source.

Each of tag 110 and tracker 120 may include various other computerizedcomponents. For instance, communication buses may be used forcommunication between wireless receiver interface 122 and processingsystem 121. Various non-transitory computer readable storage mediums maybe present, such as to store signal strength datastore 125. In someembodiments, tracker 120 may be physically integrated as part ofmotorized tracking assembly 130. In other embodiments, tracker 120 mayoutput in indication of direction by direction output interface 126 tosome other device or system, such as a computer system which may use thedirection information for a purpose other than pointing a mount.

FIGS. 2A-2D illustrate embodiments of tag antenna transmission patternsand tracker antenna receiver patterns. In FIG. 2A, tag device 250 isillustrated. Tag device 250 may represent an embodiment of tag device110 of FIG. 1. Tag device 250 may have an antenna radiation pattern of210 for all of its antennas. However, at a given time, only a singleantenna may be active. In embodiment 200A, an antenna that has antennaradiation pattern 211 may be the only antenna of tag 250 that is active.Antenna radiation pattern may represent the main lobe region of theantenna radiation pattern. The main lobe may have an angle ofapproximately 90°. The illustrated edge of antenna radiation pattern 211may represent the portion of the antenna radiation pattern having apower level within 3 dB of the center of the main lobe. In someembodiments, located between the main lobes of the antenna radiationpatterns is a null region having zero or almost no signal strength.

While tag 250 is active transmitting one or more messages via theantenna that has antenna radiation pattern 211, tracker 230 may receiveat least a portion of the one or more messages using each antenna oftracker 230. Tracker 230, as illustrated, has sixteen antennas, each ofwhich has a main lobe antenna radiation pattern illustrated. The mainlobe of each antenna may have an angle of approximately 22.5°. Theillustrated edge of each antenna radiation pattern may represent theportion of the antenna radiation pattern having a power level within 3dB of the center of the main lobe. Antenna radiation pattern 220represents each antenna's receive antenna radiation pattern of tracker230. Each of the antennas associated with these antenna radiationpatterns may be activated one at a time in a sequence, such asillustrated by arrow 225. For instance, the antenna of antenna radiationpattern 221 may be activated, then the antenna of antenna radiationpattern 222 may be activated, then the antenna of antenna radiationpattern 223 may be activated, and so on. Each antenna and associatedantenna radiation pattern may be used to measure a signal strength ofthe one or more messages received from the antenna of tag 250 thattransmits in antenna radiation pattern 211. In some embodiments, tag 250may transmit sixteen messages, such that one message is received by eachantenna of tracker 230. Tag 250 may transmit using the antennaassociated with antenna radiation pattern 211 for a defined period oftime such that each antenna of tracker 230 is used to measure signalstrength.

Such a transmission by tag 210 and measurement of signal strength bytracker 230 may repeat for each antenna of tag 210. In FIG. 2B, anantenna that has antenna radiation pattern 212 may be the only antennaof tag 250 that is active. Antenna radiation pattern 212 may representthe main lobe region of the antenna radiation pattern. The main lobe mayhave an angle of approximately 90°. The illustrated edge of antennaradiation pattern 212 may represent the portion of the antenna radiationpattern having a power level within 3 dB of the center of the main lobe.While tag 250 is active transmitting one or more messages via theantenna that has antenna radiation pattern 212, tracker 230 may receiveat least a portion of the one or more messages using each antenna oftracker 230. Each of the antennas of tracker 230 may be activated one ata time in a sequence. For instance, the antenna of antenna radiationpattern 221 may be activated, then the antenna of antenna radiationpattern 222 may be activated, then the antenna of antenna radiationpattern 223 may be activated, and so on. Each antenna and associatedantenna radiation pattern may be used to measure a signal strength ofthe one or more messages received from the antenna of tag 250 havingantenna radiation pattern 212. Again, tag 250 may transmit using theantenna associated with antenna radiation pattern 212 for a definedperiod of time such that each antenna of tracker 230 is used to measuresignal strength.

In FIG. 2C, an antenna that has antenna radiation pattern 213 may be theonly antenna of tag 250 that is active. Antenna radiation pattern 213may represent the main lobe region of the antenna radiation pattern. Themain lobe may have an angle of approximately 90°. The illustrated edgeof antenna radiation pattern 213 may represent the portion of theantenna radiation pattern having a power level within 3 dB of the centerof the main lobe. While tag 250 is active transmitting one or moremessages via the antenna that has antenna radiation pattern 213, tracker230 may receive at least a portion of the one or more messages usingeach antenna of tracker 230. Each of the antennas of tracker 230 may beactivated one at a time in a sequence. For instance, the antenna ofantenna radiation pattern 221 may be activated, then the antenna ofantenna radiation pattern 222 may be activated, then the antenna ofantenna radiation pattern 223 may be activated, and so on. Each antennaand associated antenna radiation pattern may be used to measure a signalstrength of the one or more messages received from the antenna of tag250 having antenna radiation pattern 213. Again, tag 250 may transmitusing the antenna associated with antenna radiation pattern 213 for adefined period of time such that each antenna of tracker 230 is used tomeasure signal strength.

In FIG. 2D, an antenna that has antenna radiation pattern 214 may be theonly antenna of tag 250 that is active. Antenna radiation pattern 214may represent the main lobe region of the antenna radiation pattern. Themain lobe may have an angle of approximately 90°. The illustrated edgeof antenna radiation pattern 214 may represent the portion of theantenna radiation pattern having a power level within 3 dB of the centerof the main lobe. While tag 250 is active transmitting one or moremessages via the antenna that has antenna radiation pattern 214, tracker230 may receive at least a portion of the one or more messages usingeach antenna of tracker 230. Each of the antennas of tracker 230 may beactivated one at a time in a sequence. For instance, the antenna ofantenna radiation pattern 221 may be activated, then the antenna ofantenna radiation pattern 222 may be activated, then the antenna ofantenna radiation pattern 223 may be activated, and so on. Each antennaand associated antenna radiation pattern may be used to measure a signalstrength of the one or more messages received from the antenna of tag250 having antenna radiation pattern 214. Again, tag 250 may transmitusing the antenna associated with antenna radiation pattern 214 for adefined period of time such that each antenna of tracker 230 is used tomeasure signal strength.

FIG. 3 illustrates an embodiment 300 of a scenario in which an obstacleis present that affects signal strength measurements made by thetracker. In embodiment 300, a wall may be obstacle 301. Tag 250 maysequence through transmitting message through each antenna, asillustrated in FIGS. 2A-2D and as illustrated by arrow 320. Similarly,tracker 230 may progress through making signal strength measurementsthrough each antenna for each transmitting antenna of tag 250. Inembodiment 300, due to reflection from obstacle 301, the signal strengthmeasured by tracker 230 will be higher for antenna radiation pattern 213than antenna radiation pattern 214 or antenna radiation pattern 212.However, antenna radiation pattern 211 will be the strongest and willhave the flattest distribution of signal strength measurements acrossmultiple antenna radiation patterns of tracker 230. Having the“flattest” distribution refers to having a smaller amount of signalstrength drop off between adjacent antenna measurements of tracker 230than when other antennas of tag 250 are transmitting. For example, whenthe antenna associated with antenna radiation pattern 211 istransmitting, the difference between signal strength measurements madeusing antenna radiation pattern 312 and antenna radiation pattern 311may be 3 dB and the difference between signal strength measurements madeusing antenna radiation pattern 312 and antenna radiation pattern 313may be 4 dB. However, when the antenna associated with antenna radiationpattern 213 is transmitting, the difference between signal strengthmeasurements made using antenna radiation pattern 312 and antennaradiation pattern 311 may be 5 dB and the difference between signalstrength measurements made using antenna radiation pattern 312 andantenna radiation pattern 313 may be 7 dB. As such, the signal strengthdistribution is flatter when antenna radiation pattern 211 of tag 250 isactive.

FIG. 4 illustrates an embodiment 400 of a scenario in which multipleobstacles are present that affects signal strength measurements made bythe tracker. In embodiment 400, multiple obstacles, which may be walls,are present: obstacles 402, 403, 404, and 405. Tag 250 may sequencethrough transmitting message through each antenna, as illustrated inFIGS. 2A-2D and as illustrated by arrow 320. Similarly, tracker 230 mayprogress through making signal strength measurements through eachantenna for each transmitting antenna of tag 250. In this scenario, noparticular transmitting antenna of tag 250 will result in signalstrength measurements at tracker 230 that are significantly greater thanother antennas of tag 250. However, signal strength measurements madewhile the antenna of tag 250 that has antenna radiation pattern 211 willresult in the flattest measured signal strengths by tracker 230 acrossits antennas.

Therefore, for example, if a greatest signal strength measurement ismade using antenna radiation pattern 420 while tag 250 is transmittingusing antenna radiation pattern 211. A drop in signal strength may beobserved in the signal strength measured using antenna radiation pattern421 and a further signal strength decrease may be measured using antennaradiation pattern 422. In contrast, when antenna radiation pattern 212is active, a greatest signal strength measurement may be made usingantenna radiation pattern 422 (due to a reflection off obstacle 403). Adecrease in signal strength may be measured using antenna radiationpattern 421, but an increase to a greater signal strength than antennaradiation pattern 421 but less than antenna radiation pattern 422 may bemeasured using antenna radiation pattern 420. Thus, when antennaradiation pattern 212 is active, a flat signal strength measurementpattern may not be detected due to the presence of one or more localmaximums. For the flattest detected signal strength measurement pattern,the direction may be determined based on the antenna radiation patternthrough which the greatest signal strength measurement was measured. Inthis example, antenna radiation pattern 420 exhibits the highestreceived signal strength with the flattest overall set of signalstrength measurements across all of the antennas of tracker 230 whileantenna radiation pattern 211 of tag 250 is active.

FIG. 5 illustrates an embodiment 500 of a scenario in which multipleobstacles are present that affects signal strength measurements made bythe tracker. In embodiment 500, multiple obstacles, which may be wallsor other objects, are present: obstacles 501, 502, 503, 504, 505, 506,and 507. Tag 250 may sequence through transmitting message through eachantenna, as illustrated in FIGS. 2A-2D and as illustrated by arrow 320.In embodiment 500, no signal strength measurement made when any ofantenna radiation patterns 211-214 are active may be greater than adefined threshold difference as compared to other antenna radiationpatterns. Further, due to interference of obstacles 501-507, no measuredsignal strength distribution may be identified as flattest. That is,each signal strength distribution for the different antenna radiationpatterns of tag 250 measured by tracker 230 may not meet a minimumthreshold to be selected as a flattest signal strength distribution.

In order to determine the direction from tracker 230 to tag 250, overallpower measurements made by each antenna of tracker 230 may be summed.For example, for the antenna that is associated with antenna radiationpattern 520, the signal strength received via that antenna may be summedfor antenna radiation patterns 211-214 of tag 250. Summations may becreated for each antenna of tracker 230. Once the summations arecalculated, a maximum signal strength value may be selected from thesummations. In both directions (clockwise and counterclockwise) from themaximum signal strength, a signal strength below a defined minimumsignal strength threshold may be located. The direction to tag 250 fromtracker 230 may be estimated to be half of the angle between the twoantennas identified as having the signal strength below the definedminimum signal strength. Further detail is provided in relation to FIG.6.

FIG. 6 illustrates an embodiment 600 of using null signal strengthmeasurements to estimate a direction of a tag. Embodiment 600 canrepresent tag 250 in embodiment 500. In embodiment 600, a “null” signalstrength measurement (that is, below a defined minimum signal strengththreshold) was present in the summations of signal strength of theantenna radiation patterns 601 and 602. The maximum signal strengthmeasurement may have been identified in the summation of signal strengthof antenna radiation patterns 603. In embodiment 600, an angle betweenthe centers 611 and 612 of antenna radiation patterns 601 and 602 isdetermined. The direction to the tag is estimated as half of this angle,represented by point 620 and direction 621 to the tag.

Various methods may be performed using the systems detailed in relationto FIG. 1 through FIG. 6. FIG. 7 illustrates an embodiment of a method700 for using a wireless camera tracking system. Method 700 may beperformed using wireless camera tracking system 100 of FIG. 1. Theprecise number of antennas present for the tag and the tracker may varyby embodiment. In many embodiments, the tracker will have a greaternumber of antennas than the tag. At block 710, signal strengthmeasurements may be made using multiple different antennas of a trackerdevice. The tracker may measure a signal strength at each of itsantennas while each antenna of the tag is transmitting. Therefore, thenumber of signal strength measurements made by the tracker may be thenumber of antennas of the tracker multiplied by the number of antennasof the tag. The tag may transmit from each of its antennas for a definedperiod of time. Therefore, the tag transmitting is performed in a TDMAarrangement. Each message transmitted by the tag may indicate: 1) anidentifier of the tag; and 2) an indication of the antenna from whichthe tag is transmitting.

At block 720, it may be determined whether a maximum signal strengthmeasured from a particular tag antenna by a particular antenna of thetracker is greater than signal strength measurements made using otherantennas of the tracker and is at least a threshold difference greaterthan a maximum signal strength measured from each other tag antenna byantennas of the tracker. If so, this is a strong indication that thedirection from the tracker to the tag is the direction in which theantenna radiation pattern of the particular antenna of the tracker thatmeasured the maximum signal strength is pointed. Therefore, at block725, the tracker may determine the direction from the tracker to the tagbased on this determination of the maximum signal strength in thedirection in which the antenna's antenna radiation pattern is pointed.If at block 720 a maximum signal strength measured by a particularantenna of the tracker is not at least a threshold difference greaterthan the maximum signal strength measured by other antennas of thetracker, method 700 may proceed to block 730.

At block 730, rather than focusing exclusively on an absolute maximum ofsignal strength, the flatness of a distribution of signal strengthmeasurements across multiple antennas of the tracker may be analyzed. Ina situation with little interference, it can be expected that aparticular antenna of the tracker will measure a greatest receivedsignal strength. For antennas in either direction from the antenna withthe greatest received signal strength, a drop-off in signal strength maybe expected to be measured. For example, a 3 dB signal strength drop-offas compared to the greatest received signal strength may be required tobe measured within a predefined number of antennas from the antenna withthe greatest received signal strength. If not, the measured signalstrength pattern may be determined to be flat. In situations withinterference, reflection, or the tag being close to the tracker, asignal strength distribution across multiple antennas of the tracker maybe relatively flat.

At block 730 if signal strength measurements do not decrease at least athreshold amount across multiple antennas of the tracker for aparticular transmitting antenna of the tag as measured from a maximumsignal strength measurement of an antenna of the tracker, a flatdistribution may be present and method 700 may proceed to block 740.

If block 730 results in a “no” determination, the measured RSSI valuesmay be used to reconstruct the radiation pattern. For instance, if theRSSI measurements do not result in a particular antenna being identifiedas having the highest received signal strength of the tracker, adirection to the tag device may be identified by selecting an anglebetween the two antennas that have the highest received signal strength.

If block 730 results in a “yes” determination, an analysis similar to asdetailed in relation to FIGS. 5 and 6 may be performed at blocks740-760. At block 740, for each antenna of the tracker, a summation ofsignal strength measurements may be made by the tracker for eachtransmitting antenna of the tag. Therefore, if the tag has fourantennas, for each antenna of the tracker, the four measurements madeusing the antenna of the tracker for each antenna of the tag may besummed. At block 750, an antenna of the tracker may be identified havingthe greatest summed signal strength measurement. On either side of thisantenna, the tracker may identify an antenna of the tracker at which thesignal strength is below a defined minimum signal strength threshold. Assuch, an angle is present between the two antennas, wherein the angleincludes the direction of the antenna beam pattern of the trackerantenna having the greatest summed signal strength measurement.

At block 760, a direction may be calculated based on the direction inwhich the to identify tracker antennas have the main lobes of theirrespective antenna radiation patterns. To calculate the direction, anangle between the center of each of the main lobes of the antennaradiation patterns may be determined. The center of the angle may beidentified as the direction from the tracker to the tag. In someembodiments, whether or not an accurate direction can be determined atblock 760, (for example, an accurate direction may not be possible todetermine if two antennas below the minimum threshold cannot beidentified), method 700 may result in the tracker transmitting updatedsettings to the tag. For instance, the tracker may instruct the tag tochange a transmission frequency, a transmission power level, and/or howfrequent messages are transmitted.

At block 770, a motorized tracking assembly may be controlled by thetracker device based on the determined direction. Therefore, the trackermay output an indication of a direction to the motorized trackingassembly. The indication of this direction may be used by the motorizedtracking assembly to adjust the direction in which a mount of themotorized tracking assembly is pointed. A camera or some other devicemay be attached to the amount such that when the direction is adjustedby the motorized tracking assembly, the direction in which the devicethat is mounted to the amount is also adjusted.

While each step of method 700 may be performed by an onboard processingsystem of the tracker, it should be understood that in otherembodiments, data may be transmitted, such as via a network, to a remotedevice or system, such as a cloud-based processing system. Thecloud-based processing system may perform the calculations as detailedin method 700 and may control or otherwise provide the determineddirection to the motorized tracking assembly at block 770. In stillother embodiments, a motorized tracking assembly may not be controlled,rather the determined direction may be used for some other purpose. Forexample, a display may be presented that indicates a directiondetermined to a tag.

The methods, systems, and devices discussed above are examples. Variousconfigurations may omit, substitute, or add various procedures orcomponents as appropriate. For instance, in alternative configurations,the methods may be performed in an order different from that described,and/or various stages may be added, omitted, and/or combined. Also,features described with respect to certain configurations may becombined in various other configurations. Different aspects and elementsof the configurations may be combined in a similar manner. Also,technology evolves and, thus, many of the elements are examples and donot limit the scope of the disclosure or claims.

Specific details are given in the description to provide a thoroughunderstanding of example configurations (including implementations).However, configurations may be practiced without these specific details.For example, well-known circuits, processes, algorithms, structures, andtechniques have been shown without unnecessary detail in order to avoidobscuring the configurations. This description provides exampleconfigurations only, and does not limit the scope, applicability, orconfigurations of the claims. Rather, the preceding description of theconfigurations will provide those skilled in the art with an enablingdescription for implementing described techniques. Various changes maybe made in the function and arrangement of elements without departingfrom the spirit or scope of the disclosure.

Also, configurations may be described as a process which is depicted asa flow diagram or block diagram. Although each may describe theoperations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be rearranged. A process may have additional steps notincluded in the figure. Furthermore, examples of the methods may beimplemented by hardware, software, firmware, middleware, microcode,hardware description languages, or any combination thereof. Whenimplemented in software, firmware, middleware, or microcode, the programcode or code segments to perform the necessary tasks may be stored in anon-transitory computer-readable medium such as a storage medium.Processors may perform the described tasks.

Having described several example configurations, various modifications,alternative constructions, and equivalents may be used without departingfrom the spirit of the disclosure. For example, the above elements maybe components of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the invention.Also, a number of steps may be undertaken before, during, or after theabove elements are considered.

What is claimed is:
 1. A wireless tracking system, comprising: a tagdevice, comprising: a first plurality of antennas, each antenna of thefirst plurality of antennas having an antenna radiation pattern pointedin a different direction; a wireless transmitter interface thattransmits via each antenna of the first plurality of antennas; a tagdevice processing system that causes the wireless transmitter interfaceto transmit a sequence of messages via the first plurality of antennas,wherein: each message of the sequence of messages is transmitted via adifferent antenna of the first plurality of antennas; each message ofthe sequence of messages is transmitted for a defined time period; andeach message of the sequence comprises an identifier of the antenna ofthe first plurality of antennas from which it is transmitted; and atracker device that tracks a direction from the tracker device to thetag device, the tracker device comprising: a second plurality ofantennas, each antenna of the second plurality of antennas having anantenna radiation pattern pointed in a different direction; a wirelessinterface receiver that performs a plurality of signal strengthmeasurements, wherein each signal strength measurement is made via adifferent antenna of the second plurality of antennas during the definedtime period; and a tracker device processing system configured to:receive the plurality of signal strength measurements; and determine thedirection from the tracker device to the tag device using the pluralityof signal strength measurements.
 2. The wireless tracking system ofclaim 1, further comprising a motorized tracking assembly, wherein thetracker device processing system is further configured to output thedirection to the motorized tracking assembly, and the motorized trackingassembly is configured to physically point a mount of the motorizedtracking assembly based on the direction data.
 3. The wireless trackingsystem of claim 2, wherein the motorized tracking assembly is configuredto have a video camera mounted onto the mount.
 4. The wireless trackingsystem of claim 1, wherein the second plurality of antennas has agreater number of antennas than the first plurality of antennas.
 5. Thewireless tracking system of claim 4, wherein the first plurality ofantennas comprises four antennas with each antenna of the firstplurality of antennas having a 90 degree radiation pattern.
 6. Thewireless tracking system of claim 5, wherein the second plurality ofantennas comprises twenty-four antennas with each antenna of the secondplurality of antennas having a 15 degree radiation pattern.
 7. Thewireless tracking system of claim 1, wherein the tracker deviceprocessing system being configured to determine the direction from thetracker device to the tag device using the plurality of signal strengthmeasurements comprises: determining that the signal strengthmeasurements made by the wireless interface receiver from the sequenceof messages transmitted by the first plurality of antennas areinconclusive as to which of the first plurality of antennas is pointedtowards the tracker device; in response to the determining, identifyinga first antenna of the second plurality of antennas and a second antennaof the second plurality of antennas through which signal strengthmeasurements were made that were below a minimum threshold value andbetween which the signal strength measurements were above the minimumthreshold value; and determining the direction from the tracker deviceto the tag device as a center of an angle between the first antenna andthe second antenna.
 8. The wireless tracking system of claim 1, whereinthe wireless transmitter interface transmits using the IEEE 802.11astandard.
 9. The wireless tracking system of claim 1, wherein eachmessage further comprises a tag identifier that identifies the tagdevice.
 10. The wireless tracking system of claim 1, wherein the tagdevice further comprises a battery compartment and the tag device isexclusively powered by one or more batteries installed in the batterycompartment.
 11. A method of using a wireless tracking system, themethod comprising: transmitting, by a tag device of the wirelesstracking system, a signal via each tag antenna of a plurality of tagantennas of the tag device, wherein: each tag antenna of the pluralityof tag antennas is pointed in a different direction; and each signal istransmitted sequentially; receiving, by a tracker device of the wirelesstracking system, each signal transmitted via each tag antenna using eachtracker antenna of a plurality of tracker antennas of the trackerdevice, wherein: each signal identifies the tag antenna of the pluralityof tag antennas of the tag device from which the signal was transmitted;performing, by the tracker device, a plurality of signal strengthmeasurements for each signal received via each tracker antenna of theplurality of tracker antennas; and determining the direction from theplurality of tracker antennas to the tag device using the plurality ofsignal strength measurements.
 12. The method for using the wirelesstracking system of claim 11, further comprising: outputting, by thetracker device, direction data indicative of the direction to amotorized tracking assembly, and the motorized tracking assembly isconfigured to physically point a mount of the motorized trackingassembly based on the direction data.
 13. The method for using thewireless tracking system of claim 12, further comprising: capturingvideo using a video camera that is mounted to the mount of the motorizedtracking assembly.
 14. The method for using the wireless tracking systemof claim 11, wherein the plurality of tracker antennas has a greaternumber of antennas than the plurality of tag antennas.
 15. The methodfor using the wireless tracking system of claim 11, wherein determiningthe direction to the tag device using the plurality of signal strengthmeasurements comprises: determining that the signal strengthmeasurements made from the signals transmitted by the first plurality ofantennas are inconclusive as to which of the plurality of tag antennasis pointed towards the plurality of tracker antennas; in response to thedetermining, identifying a first antenna of the plurality of trackerantennas and a second antenna of the plurality of tracker antennasthrough which signal strength measurements were made that were below aminimum threshold value and between which the signal strengthmeasurements were above the minimum threshold value; and determining thedirection to the tag device as a center of an angle between the firstantenna and the second antenna.
 16. The method for using the wirelesstracking system of claim 11, wherein the tag device transmits thesignals using the IEEE 802.11a standard.
 17. The method for using thewireless tracking system of claim 11, wherein each signal furthercomprises a tag identifier that identifies the tag device.
 18. Themethod for using the wireless tracking system of claim 11, furthercomprising: exclusively powering the tag device using one or moreon-board batteries.
 19. The method for using the wireless trackingsystem of claim 11, wherein the plurality of tag antennas comprises fourtag antennas.
 20. The method for using the wireless tracking system ofclaim 11, wherein the plurality of tracker antennas comprisestwenty-four tracker antennas.